A cobpobation oe dela



March 16- 1926.

R. G. RICHARDSON RELAY AUTOMATIC TELEPHONE SYSTEM 3 Sheets-Sheet 1 Original Filed Jilly 28, 1920 Inu'sn 0r Kc/dnE E. Ezchardscm R. G. RICHARDSON RELAY AUTOMATIC TELEPHONE SYSTEM March 16 1926.

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1 f Tr Inueulnr KN a w T M N N P U 5 d F a h w E E Roch-L5 March 1 63-1926. R 16,293

R. G. RICHARDSON RELAY AUTOMATIC TELEPHONE SYSTEM Original Filed July 28, 1920 3 Sheets-Sheet 5 limp- Eudne E Emhardsun standai Reissued Mar. 16, 1926 UNITED STATES PATENT OFFICE.

RODNEY G. OI OHICAGO, ILLINOIS, AQSIGNOB, BY MESNE ASSIGNMENTS,

TO AU'IOKATIC ELECTRIC, INC., 01' CHICAGO, ILLINOIS, A CORPORATION OF DELA- WABE.

Original N0. 1,508,083, dated calling subscribers'solely through the me-.

dium of rela s at the central exchange and the object o the invention is the provis on of a simple and efficient systemof this kind which is especially adapted for use in small isolated nvate exchanges, although there are certain features OflIIl rovement which a will no doubt be of utility in Iarger systems.

It is of course necessary in all relay sys-' tems to keep the number of relaysdown to a minimum and various complicated trunkingsystems have been devised with this object in .view. I find however that in very-small systems nothing'is gained by resorting to such .ex edients and I employ therefore a trunkingsystem in which a'plurality of trunks orlink circuits are provided, all alike and in one group, which are accessible to all the subscribers lines an'd which have access to all the subscribers hnes. When a calling subscriber removes his receiver his line is automatically connected with atrunk line extending to an idle relay connecting device. This connecting device may be comparedto an automatic connector switch of well known type and isaoperated upon calling the proper digit or d1 'ts tocomplete the connection to any desire line. Two of the principal features have to do with the trunk selecting'mechanism and with the line connecting mechanism or means by which a selected trunk line is connected wit a desired called line. As to the former, an individual rela trunkselector is provided for each line w ich operates according to. an a proved principle to select always t e first i la trunlgline. Since-there is no common mechanism the trunk lines may he slipped in the multiple "between the trunk selectors so that each trunk ,Wlll be: first choiceto certain lines, thus equalizing the traflic. \Vith regard to the latter feature, the line be brie BELLY AUTOMATIC TELEPHONE SYSTEM.

August 26, 1824, Serial No. 399,528, nled July 28, 1920. Application for reissue fled July 3, 1925. Serial No. 41,439.

' connecting mechanism, an essential part of vthis mechanism 18 the counting relays,

which in this system are also the connecting relays. These relays respond to impulses from a calling station, and due to the provision of a novel control circuit, are provided only to the extent of one relay per digit, whereas so far as applicant isaware two(1 relays per digit have formerly been use These improvements, and others not'now speclfically mentioned will be fully described in the course of the explanation-of the operation of the complete system which will now .b proceeded with, reference being had to the accompanying drawings.

In the drawings, comprisi'n Figs. 1, 2 and 3, I have shown by means of t e usual circuit diagrams the essentials of a nineteen line relay automatic system, constructed according' to my invention. Fig. 4, which is placedcn the same sheet with Fig. 2, is a schematic drawing which shows an approved method ofslippling the trunks in the multiple between t e trunk selectors.

The iipparatus shownin the drawings may y described as -follows: Substation A is an automatic substation of the usual type, having in addition to the talking instrumentalities a calling device S which is used by the subscriber to control the central ofiice switchin mechanism. The line conductors 12 an 14 extend to a central point where the switchboard is located and there terminate in the individual relaytrunk' selector C. The trunk selector C comprises the line and cut 011? relays 16 and 15 and the trunk connecting relays'l'f, 18, and 19.

As shown herein the system isintended to serve a total of nineteen lines -a nd th'reetrunks will usually be. enough, though one or twomoremay be furnished if considered necessary. At any rate only three trunks are shown, the conductors 20 to 23., inclusive,

being the conductors of the first'trunk, conductors-24 to 27, inclusive the second, and

conductors 28 to. '31 inclusive, the third. Relays 17, 18, and 19 are adapted to be sepa rately ener 'zed, aswill he-explained, and are adapt to connect the line of substation A with the severaltrunki lines, respectivel individual trunk selector C which is in all respects like the-trunk selector C. Each of the other lines in the system is equipped in a similar manner and has access to the three trunk lines shown, which. are multipled to contacts in the connecting relays of the trunk selectors according to the plan shown in Fig. 4. Referring to this diagram, since there are' three trunk lines, the lines aredivided into three groups.

Lines 1 to '6, inclusive, constitute the first group; lines 7 to 9, inclusive, and 01 to 03, inclusive, constitute the second group; while lines 04 to 00, inclusive, constitute the third group. The three trunk lines are multipled straight to all the lines of the first group, but there is a slip between the first and second (groups and again between the second an 'thi grou s. trun first choice to the-lines of the first cap, the second trunk first choice to the fi l 16S of the second group, and the third trunk first choice to the lines of thethird group, and is the usual expedient used in automatic systems to evenly distribute the To roceed with the explanation, only the secon trunk line, comprising conductors 24 to 27, inclusive, Fig. 1, is'shown complete. These conductors extend to Fig. 2 where they terminatein the group of relays which is mdicated by the reference character D.

' These relays may be termed a connector, and

include the usual line and release relays 100 and 101 and other relays which have to do with the busy testing, the signalling of the called line, etc.

The connector D has no wipers or mechanism of an kind and the connection to desired calle linesiscompleted by means of the counting relays which are shown in Fig.

3. There are twenty counting relays, one for each line in'the system, and an extra relay, the one corresponding to the digit 0, to which no line is assigned. Only the first three relays, the extra O'digit relay and the three succeeding relays are shown, as this is suflicient to show how the system works.

The relays omitted are wired the same as the ones shown. The. lines are multi led corresponding counting relays in the t ree trunks in the same way that linesl and 2,

which are the lines of substations A and A, are connected to. the counting relays "land 2 of the second trunk. The reference characters assigned to the counting relays in the drawing it will be observed, are the same as the telephone numbers of the correspondin lines.

e reference character E, Fig. 2 denotes a group of four relays which are used to control the counting relays responsive to current impulses transmitted over the trunk by a calling subscriber. These relays constitute a kind of translating device the op- This arrangement makes the first ting up a connection. For this purpose it.

will be assumed that the subscriber at substation A desires to call the subscriber at substation A and the operations involved in setting up'the connection will be ex lained.

-When thereceiver is removed at su station A a circuit is *closed' in the usual manner for the line relay 16. Upon energizing, relay 16 connects ground to the upper winding of relay 17 by means of its; armature 40, and at the same time by'means of its armatures 41 and 42 extends the ground connection to the upper windings of relays 18 and 19, respectively. The circuit for relay 18, it will be observed, includes the armature 43 of relay 17, while the circuit of relay 19 includes this same armature and also the armature 45 of .relay 18. The other terminal of the upper windingof relay 18 is connected to the test conductor 25 which goes to the un ounded pole of the battery at relay 101 o the connector D, provided the trunk is idle- Relays 17 and 19 are similarly connected to' test conductors 21 and 29.' It will be assumed now that the first trunk is busy, while the second and third trunks are idle. Test conductor 21, then,

'will be'dis'connected from battery and relay .45 and the latter relay at once falls back.

In additiom'relay 18 connects line conductors 12 and 14 to the? trunk line conductors 24 and 27 by means of its armatures 44 and 47, and also connects the private normal conductor 13 to the release trunk conductor 26 at armature 46. Atthe same armature the release trunk conductor is connected tothe locking winding of relay 18. 1

When the conductors of the calling line are connected with the line conductors of the second trunk line asexplained above, the double wound line relay 100 oftheconnector D is energized over the line circuit and closes the circuit of the slow acting release relay 101. 'Upon energizing, thelatter relaydisconnects the battery from test-conductor 25 at armature 107 and at armature 108 connects ground to the release trunk conductOr 26. By the former operation the trunk is made busy, and by the latter the locking winding of rela 18 is energized. The cut off relay 15, whlch is also connected to conductor 13, is energized in parallel with the I gfron conductor 127 when the latter relay locking winding f may 18 and. operates to disconnect the two line conductors 12 and 14 from the line relayj16 and from ground,

respectively. Line rela 16 is now deenergized and breaks the circuits of the trunk connecting relays, relay 18 being held in uperatedposition by the circuit through its locking winding.

Everything is now in readiness for the calling subscriber to 0 rate his callin 'device in accordance-wit the number 0 desired line, in order to energize the proper one of the-connecting relays to complete the connection, but 'before proceeding with this it will be necessary to consider the operation of the translating device E. When'the calling device is operated-it of course interrupts the line circuit a plurality of times and the line relay 100 is deenergized a like number of times totransmit 'a series ofimpulses over conductor v124. This conductor. extends tothe translating device E where it is adapted to be connected either to conductor 131 or conductor 132, which conductors extend to the counting relays. The odd numbered relays are adapted to be'ener 'z ed over conductor 131 while the even num red relays are ada ted to be energized over condnctor132; an the function of the translating device is toconnectconductor 124 with conductors 131 and 132 in alternation so that the odd impulses will travel over the former conductor and the even impulses over the latter. This is accomplished as follows: When the slow acting release relay 101 energizes it connects the 'ungrounded pole ofthe battery to conductor 141 which is connected withconductors 126 and 127' at armatures 114 and 115 of the off normal relay 103, thus supplying battery to the relays of the translating device. The'line relay 100 being now energized, a circuit is completed over conductor 123 for relay 152 which, upon energizing, locks itself at its armature 159, and atits armature 158 connects conductor 124 (the conductor over which im ulses are trans mitted) to the upper win ing of relay 151 and also to conductor 131'.

It will now be assumed that the line relay 100- is caused to vibrate its armature 106 responsive to a series of impulses transmit-' ted by the calling subscriber. By this operation conductors 124and 123 are rounded alternately. When the line relay alls back the first time conductor 124isgrounded and a circuit is closed through the slow acting relay 104 in the connector.

ihis relay is accordingly energized and being slow acting remains in operated osition throughout the series of impulses. elay 104 at ts armature 116 places a shunt around the break contact at armature 115 of the oil normal relay so that battery will not be disconnected the the

y the deenergization of the line relay 100 pulls up. When conductor 124 is grounded an impulse of current is transmitted over I conductor 131 to the first counting relay, Fig.

'3, 'andat the same time" relay 151 of the translating device E is energized. When relay 151 pulls up it pre ares a circuit for relay 150 at armature 15 T breaks the locking circuit ofrela 152 at-armature .156, and by means of t 1e same armature closes it s own lockin circuit. Relay 152 now deener izes. In ig. 3, the No. '1 counting re lay as been energized by the ground im pulse transmitted over conductor 1'31. Upon ener izing, this relay repares a circuit for o. 2 counting re ay at armature 140, and at armature 141 closes a locking circuit for itself. This locking circuit includes a series of break contacts on the other counting relays, the conductor 129,'and the ofi normal relay 103 in the connector D. The

ofl normal relay is thus ener i'zed and at.

its armature 114 disconnects attery from conductor 126. The opening of the break contact at armature 115 has no present effect due to the fact that relay 104 is in 01;)-

erated position.

The grounding of conductor 124 by the line relay is only momentary and when this relay pulls up a ground is placed on conductor 123, .this closing the previously prea'red circuit of relay 150. U on energizmg, relay150 establishes a 100 ing circuit for itself at armature 155, breaks the locking circuit of relay 151 at the same armature,

and at armature 154 connects conductor 124 with conductor 132. The line relay 100 now falls back for the second time. the conductor 124 is grounded again and a current impulse is transmitted by way of conductor 132 to the No. 2 counting relay,

7 while at the same time relay 153 at the translating device is ener ized. Upon energizing, relay 153 closes a loc ing circuitfor itself at armature 160, breaks the locking circuit of relay 150 at the same armature, and at armature 161 prepares a circuit for relay 152.

' The No. 2 counting relay is energized by the impulse of current coming over conductor 132 and locks itself at its armature 144, at the same time breaking the lockingcircuit As a. result of the No. 1 counting relay. Relay 2 also I prepares a circuit for the No. 3 relay at armature 143. 3 g

The line relay now pulls up again and by grounding conductor 123 closes the circuit of relay 152. Upon energizing, relay 152 closes its locking circuit at armature 159, breaks the locking circuit of relay 153 at the same armature, and at armature 158 again connects conductor 124 to conductor 131 and to the'winding of relay 151. The translating device is now in the same condition that it was before the series of impulses was started. Two-impulses-havc been transmitted to the counting relays, the first over conductor 131 to relay 1, and the Sec-,

. the connection under consideration. There is only one digit in the telephone number of substation A and this is the digit 2. The

, calling subscriber will accordingly operate a digit, thereby producing two interruptions,

his calling device in accordance with this of the line circuit andcausing two deenergizations of the line relay 100. Two impulses are therefore transmitted over conductor 124,-the first proceedingover conductor 131 to energize relay 1 and the second over conductor 132 to energize relay 2, all as previously ex lained. WVhen the first counting relay pu ls up the off normal relay 103 is energized and ,remains in operated osition until the connection is released. heslow acting relay 104 is energizedby impulses over conductor 124 and as explained before remains in operated positionthroughout the series of impulses. In addition to shunting the break contact at armaturev 115 of the 01f normal relay, relay 104 connects the test conductor 128 with the uper winding-of the combined test and back ridge relay 102 as follows: Conductor 128, armature 117 and its working contact, resting contact of armature 118 and the said ar mature, and the upper winding of relay 102 r to battery. The No. 2 counting relay having been energized and locked up, the trunk conductors 122, 128, and 130 are now connected to normal conductors 12', '13, and 14' by way of 142, 145 and 146. Now. if the called line is busy there will be a ground potential on conductor 13 and relay102 will be energized. .Upon energizing, relay 102 prepares I a locking circuit for itself at its armature 110 which is closed' an instant later when the slow acting relay 104 deenergi'zes, closes lower trunk line conductor and connects its lower winding thereto .at' armature 112, at

- the same time disconnecting the ringing machine RM, and at armature 113 closes a circuit to the busyrelay. The latter relay is energized in series with the lower winding of relay 102, but interrupts its own circuit and thus produces a tone on the line which is heard by the calling subscriber and indicates to him that the desired line is engaged and inaccessible for the time being.

Having considered the case where the called line is busy, it will now be assumed that the line is idle when called. Under these circumstances when the connection is completed by the energization of the N o. 2 counting relay, as explained hereintoforc, no ground will be Tound on conductor 13' and relay 102 in the connector']) will not be energized. Instead, when the slow acting relay 104 falls back, a circuit is closed for the switching relay 105 as follows: From the grounded armature 108 of relay 101 by way of its right hand working contact, armature 110 and its resting contact, u per winding of relay 105, resting contact 0 armature 117 and the said armature, conductor 128, armature 145 and its working contact, conductor 13', and the winding of the cut off relay 15, Fig. 1, to battery. Upon the closure of the above circuit relays 105 and 15' are energized in series and the latter relay clears the line of substation A in the usual manner. Relay 105, upon ener izing, closes a locking circuit for itsel? grounds conductor 128 at armature 119, disconnects the busy relay at armature 120, and at armatures 118 and 121 closes contacts in the trunk lineconductors 122 and 130.

The connection having been established the ringer at the called station is operated by the ringing machine RM and the called subscriber is advised that a call has been received. Any approved type of ringin equipment may be used of course, depending on What is most convenient. The ringing machine shown is'exceed-ingly simple and consists of a single vibrating relay which is equipped with a weighted armature, vibrating at a frequency of about 20 cycles per second. This armature connects ground and batter alternately to the lower line conduc tor o the connectorand thus alternately charges and discharges the condenser which is in series with the ringer at the called sta- I tion. This produces analternating current through the ringer and operates it.

Relay 102 is not energized by the current through the ringer and condenser, but when the called subscriber removes his receiver this relay pulls up when the armature-of the ringingmachine RM is connected to ground at its resting contact, connects its lower winding to the lowertrunk line conductor, disconnectsthe ringing machine, and closes the talking circuit. The required connection isnow completelvestablished. The transmitterat the calling substation A islsu plied with talking battery through the win ings of the line relay 100,. while the transmitter at the called substation A is supplied with talking battery through the windings of the back ln-idge'relay 102. The talking circuit itself is shown in heavy lines and- 'will be understood without difliculty; It is to be noted that when relay 104 falls back and i i translating device and the counting relays cannot be disturbed by accidentaloperati'on of the dial or a momentary 0 ening of the line-circuit by the receiver hoo lVhen the calling subscriber hangs up his receiver the connection is released by the deenergization ofrelays 100 andlOl. When "the latter relay falls back ground is disconlay which thereupondeenergizes also.

nected from conductor 26 and the cut off relay 15 and trunk connecting relay 18 are deenergized. At the same time ground is disconnected from armature 119 of relay 105 and therefore conductor 128. As a result the switching relay 105 falls back and also the cut off relay 15' of the called line. Relay 101 also disconnects battery from the off vnormal relay-103 and this operation breaks the locking circuit of the'No. 2 counting re- Thus all the apparatus is restored to normal position.

The first nine lines have telephone numhers running from 1 to 9, and'are reached by calling a singledigit, as has been explained. The remaining ten lines have telephone numbers running from 01 to 00 and two digits or two operations of a calling dial are required to reach these lines. The digit 0 is not assigned to any line but the 0 counting relay is used as a means of. transferring to the second ten' counting" relays. This may be readily explained by assuming that line 03 is being called. When the calling subscriber calls thedigit 0,- counting relays 1 to 0 are energized successively and at the end of the series of impulses relay 0 remains pulled up. This relay is locked direct to battery by. way of conductor 125, the looking circuit including the off normal relay 103 atthe connector D. Relay 103 accordingly deener'gizes, since there-is no counting relay locked up to conductor 129, and con-' nects batterytoconductors 126 and 127, thus preparing circuits for the transmission of another series of impulses. On the next operation of the dial relays01, 02,.and 03 are energized in succession and the last relay is locked up to complete the required connec-.

tion. The looking I circuit includes conductor 129 and off normal relay 103, and the 05 normal relay is energized now and prev vents any further relay operations.

V If desired the ca acity of the system may ding ten more counting relays to each i'trunk, these added relays be increased by a being numbered from 001. to 000.- T

' twentiethrelay will then" be connected in the same way: as thetenthI-or 0 relay and will enable impulses: to "be 'senton to the new group of ten counting relays. This will callin give a capacity of 29 lines. Of course the 1 size can be increased to 39 or 49 lines in the same way, but the number of trunk lines will then have to be increased also and a limit is soon reached beyond which it will not be economical to go. I

Having described my invention that which I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

lVhat I claim is: i

1. In a telephone system, subscribers lines, trunk lines, a series of connecting relays associated with each trunk line, each series comprising a relay individual to each subscribers line, means whereby a calling subscriber. can connect with an idle trunk line, means whereb the calling subscriber can energize the re ays associated with the connected trunk line successively by impulsestransmitted over the connected trunk line, and means for maintaining the last energized relay in operated position to com-. 7

plete the connection to a called line and to maintain said lines connected during conversation. r

- 2. In "a t'ele hone system, a trunk line comprising tal ing conductors, trunk and line connecting relays at. opposite ends of trolled by the calling subscriber for ener gizing one of said line connecting relays to connect the talking conductors of said trunk with thetalking conductors of a called line.

3. In a telephone system, a trunk line, trunk and line connecting relays at opposite ends of said trunk line, respectively, each line connecting relay being individual to a different subscribers line, means for energizing a trunk connecting relay responsive to the removal of the'receiver on a calling line to connect the callin line with'the said trunk line, means where y the calling subscribe'r can transmit impulses over the trunk -to energize said line connecting relays successivel'y, and means for maintaining one of said line connecting relays in operated position to connect the trunk with a desired called line and to maintain the said calling and called lines connected over said trun line during conversation.

4. In a telephone system, a trunk and line connecting relays at opposite ends of said trunk line, respectively, means for energizing a trunk connecting relay responsive to the removal of the receiver on a line to connect the callin line with the said trunk line, means where y the calltrunk line, I

ing subscriber can transmit impulses over the trunk line to energize said line connecting relays successively, and means for deenergizing each relay when the next one is energized, the last relay which is energized being maintained in operated position to connect the trunk line with a called line and to maintain said calling and called lines connected during conversation.

5. In a telephone system, a subscribers line, a group oftrunk lines, a trunk selector for said first line comprising a series of connecting relays, there being as many relays as there are trunk lines, a line relay operated responsive to the removal of the receiver on said subscribers line for closing energizing circuits for all of said connecting relays except those associated with busy trunk lines, a pair ofbreak contacts on each relay except the last, and circuit connectlons whereby each relay upon energizing opens the circuits of all succeeding relays in the series at its associated pair of break contacts.

6. In a telephone system, a subscribers line, a roup of trunk lines. a trunk selector for sai first line comprising a series of connecting relays, there being as many relays as there are trunk lines, a line relay operated res nsive to the removal of the receiver on 'sai subscribers line for closing energizing circuits for all of said connecting relays except those associated with busy trunk lines, a pair of break contacts on each relay except the last, circuit connections whereby each relay upon energizing opens the circuits of all succeeding relays in the series at its associated pair of break contacts, whereby only oneof said connecting relays will be completely operated, a third conductor in eachtrunk line, and means for closing a locking circuit for the operated connecting relay over the third conductor ofthe trunk line associated therewith.

7. In a telephone system, a subscribers line, a group of trunk lines, a trunk selector for said first line comprising a series of connecting relays, there being as many relays as third conductor in each trunk line, means for-closing a locking circuit for the operated connecting relay over the third conductor of the trunk line associated therewith, and a cut oil relay energized over the said third conductor in parallel with said connecting relay when the locking circuit therefor is established.

8. The combination, with a control circuit having two branches, of means for transmitting impulses of current over said circuit, means for connecting'said branches alternately to said circuit when a series of impulses is transmitted thereover, a series of relays adapted to he successively energized by successive impulses transmitted over one of said branches, and a second series of relays adapted to be successively energized by impulses transmitted over the other of said branches, of a relay for connecting each branch to, said circuit, means for energizing said relays alternately, and means for transmitting impulses over said control circuit.

11. The'combinatiomwith a control circuit having two; normally disconnected branches, of two relays for connecting said two branches, respectively, to said control circuit, a line. relay and means for intermittently operating it to transmit impulses over said control circuit, and circuit connections whereby the said first mentioned relays are operated alternatelyby said line relay while impulses are being transmitted. 1

12. The combinatiom'with a control circuit and a line relay for transmitting impulses thereover, of two branches for said control circuit, anda translator for causing the odd impulses of a series to traverse one branch and the even impulses the other branch, said translator comprising four relays and circuit connections whereby they are energized successively in response to the operation of said line relay.

13. The combination, withaline relay and a circuit therefor, of means for producing a series of interruptions in said circuit to cause saidrelay to transmit a series of impulses, a train of counting relays, circuit connections whereby a plurality of said relays are energized successively responsive to said impulses, means for retaining the last energized-relay inoperated position, and means for preventing any additional relay or relays of said train from energizing re sponsive to a second'seri'es of'impulses.

14. The combination, with a line relay and a circuit therefor, of means forlproducing a series ofinterruptions in said circuit to cause said relay to transmit a series of impulses, a train of counting relays, circuit connections whereby a plurality of said relays are energized successively responsive i i to said impulses, means for retaining the last 15. The combination, with a line relay and a circuit therefor, of means for producing a series of interruptions .in said circuit to cause said relay'to transmit a series of impulses, a train of counting relays, circuit connections whereby a plurality of said relays are energized successively responsive to said impulses, a locking circuit common to said train for-retaining the last energized relay in operated position, a stoprelay included in said locking circuit for-preventing said line relay from transmitting impulses to said counting relays, and a slowacting relay adaptedtomaint'ain its armature attracted during the series of impulses .to render the stop relay inefi'e'ctive until after the last impulse of the series has been transmitted.

16. 'The combination, with a line relay and a circuit'therefor, ofmeans for producing a series of interruptions in said circuit to cause said relay to transmit a series of impulses, a train of counting relays, circuit connections whereby a plurality of said relays are energized successively responsive to said impulses, a locking circuit common to said train for retaining the lastenergized relay in operated osition, a stop relay in- ,cluded in said locking circuit forpreventing said line relay from transmitting impulses to said counting relays, a slow-acting relay adapted to maintain its armature attracted during the series of impulses to render the stop relay ineffective until after the last impulse of the series has been transmitted, and a second locking circuit for a particular one of said counting relays, said second looking circuit excluding said'stop relay, where by if a particular series of impulses is transmitted the first time'the counting relays are able to respond'to a second series.

17, In a telephone system, a trunk line, means for connecting a calling line to said trunk line, a train of countin relays, mul- I tiple trunk contacts on each re ay connected to the talking conductors of said trunk line, indiv dual contacts on each relay-connected to the line conductors ot a particular subscribers line, and means controlled over the calling line for energizing any counting relay to cause the engagement of its, as sociated multiple and individual contacts to establish a talking connection, with a desired called line. i

18. In a telephone system, a trunk line,

\ means for connecting a calling line to said trunk line, a train of counting relays, multipie trunk contacts on ,each relay connected to the talking conductors'of said trunk line, individual contacts on each relay connected to the line conductors of a particular sub scribers line, a line relay bridged across said trunk line and .controlled from the calling line to transmit impulses for operating said countingv relays] successively, and

means for maintaining the last energized relay in operated position to establish a talking connection between the said calling line and called line by way of its associated multiple and individual contacts.

19. In a telephone system, a trunk line, a relay at one end of said trunk line for "connecting said trunk line to a callirigline, means comprising a train of counting relays at the other end of said trunk line for connecting said trunk line with any desired called line, the saidcounting relays being responsive to the impulse sender on the calling line, and means in said trunk line for supplying talking current to the calling ,and called lines through contacts on said first relay and an energized counting relay, respectively.

20. In a telephone system, a trunk line,

a relay atone end of said trunk line for I connecting said trunk line to a calling line,

means comprising a train of counting relays at the other end of said trunk'line for con necting said trunkline 'with any desired means comprising'a train of counting relays at the other endof saidtrunk line for connecting said trunk line with any desired called line, the said counting relays being responsive to the impulse sender on the calling line, normally open contacts in said trunk line, a switching relay for closing said contacts, means for'testing the called line through contacts on an energized counting relay, means for operating said switching relay if the called line is, idle, and means for preventing the operation of said switch- 7 ing relay if the called line is busy.

22'. A telephone system including a selector switch having a series of relays, a plurality of lines selectable by said relays, an impulsing circuit for ener izing the relays in succession, means for maintaining the last relay of the series energized to select the desired line'and for de-energizing the previously energized relays of the series, busy signaling means, automatic testing means for connecting a calling subscribers line with the said selected desired line" if said last line is idle, and to connect said busy signaling means in a circuit with the calling line if said selected desired line is busy.

723. A telephone system including a .selector switchhavin a series ofrelays, a plurality of lines se ectable by said relays, an impulsing circuit for energizing the relays in succession, means for maintaining the last relay of the series energized to select the desired line and for de-energizing t e previously energized relays of the series, automatic testing means for connecting a calling subscribers line 'with the said selected desired line if said last line is idle, and means ,for

either signaling the said desired line if it a is idle, orfor transmitting a bus signal to the said calling line if said desired line is busy. i

24.-A telephone system including a selector switch, having a series ofrelays, a calling line and a plurality of lineszselectable by said relays, means for operating said relays in rotation and means for maintainin the last relayof the series 0 rated to se ect. and connect the desired cal ed line in.

circuit with said called line and for deenergizing the previously energized relays of .t

selected line is idle to-apply ringing current to said selected line, said test means not being aflected by said last means if said selected line is busy whereby a busy. signal to energize operated to select one of said lines, and automatic test means for connectin a callingilinewith said selected line if said selected line is idle. v

26. A telephone system including a selec tor switch having'a series of relays, a plu- 1e series, automatic test means; and means for operating said test means f the 30 by said relays,

rality of called lines adapted to be selected by said relays, a calling line and means controlled oversaid calling line for operating the relays of the series in rotation, means for maintaining the last 0 erated relay of the series energized to se ect one of said called lines, and for restoring the previously operated relays of the ser es, test means,

other means for efi'ecting'said first means to cause the operatlon of said test means to connect said selected called line in circuit with said calling line if said called lineis idle end to connect ringing meansto said called me. 27, A telephone system including acalling .subscribers line anda plurality of calle subscribers lines, a selector switchhavin'g a series of rela s, an impulse circuit for energizing the re ays in succession," means for" de-energizing all of the relays of the series that have beenoperated except the last one, said last-rela remain' *ener ized to connect the calling subscri eris hneiwith the called 'subscribersline, means for ringing the called subscriber, and means for automatically disconnecting ringing current from the called subscribers line.

28. A telephone system including a series of relays, a calling line, a plurality of selectable called lines adapted to be selected by i said switching relays, impulse means for successively. energizing said relays, means. :for maintaimng the last energized relay of the series operated to select one of said called lines while the previously energized relay of the series returns to normal, automatictest means for interconnecting Said calling line andv said selected line. and for connectin ringing means to said called line if said se ected line is idle and for prevent-vngthe interruption or and the application 'of ringing. current to saidselected line if busy, and means for rendering said calling line busy when said line and said lines are in use. A

Signed by me at Chicago, Cook County, Illinois, this 29 day of June, 1925.

- RODNEY G. nIcHARnsos. 

